The "open" end goes to the front, The recoil spring plug should have a dimple on the inside that the spring locks on to. Before you push the spring home, give the plug a turn until it locks on the spring. JMB designed the dimple for that reason.
------------------ Ne Conjuge Nobiscum "If there be treachery, let there be jehad!"
Some of the "clones" don't have the dimple. I guess, like Sport says, they didn't know what it was for and dropped it. Or it costs .0003 cents, and is too expensive.